I. Field of the Present Invention
The present invention relates generally to workpiece holders, and more particularly to a workpiece holder having a linearly displaceable bar whose movement simultaneously locks the workpiece horizontally and vertically in a fixed position.
II. Description of the Prior Art
While there are many previously known workpiece clamps, most devices for clamping workpieces that have curved peripheral surfaces are often complex and complicated. In particular, since the curved surface can roll when engaged against flat guide walls, it can be extremely difficult to retain the workpiece in a fixed position for a machining operation. As a result, workpiece holders are often particularly shaped in the configuration of a workpiece so that the workpiece is stably supported in a fixed position for machining. Unfortunately, such particularly configured workpiece holders often require that each workpiece be individually positioned and removed from a workpiece holder and such workpiece holders are not well adapted for use in production line assembly. Although it has been known to mechanize the delivery and extraction apparatus, such apparatus can be extremely complex when the workpiece must be accurately positioned in the conforming cavity and substantially increases the cost of the production operation.
Another previously known workpiece holder for locking circular workpieces in a fixed position for machining comprises three or more radially aligned jaw members which are driven radially inwardly to engage the circular peripheral edge of a workpiece at three spaced circumferential points. However, the synchronization of movement of the arms along three different directions can be rather complex, especially when the arms must be retracted from a workpiece production line path. Moreover, each arm must be accurately aligned so as to properly position the workpiece at a workpiece station for accurate engagement by a machining tool.